A conventional air suspension device is a cheap but effective way to absorb shocks transferred from the rugged road to the bicycle frame. The air suspension device basically is a cylinder in which a piston is movably received in the cylinder so that when shocks are transferred to the bicycle frame, the piston is moved to compress the air in the cylinder. By the compressibility of the air in the cylinder, the shocks can be absorbed and the rider feels comfortable when ridding on a rugged road. Nevertheless, it is a problem for the riders to pump the cylinder to provide enough pressure in the cylinder. Generally, the riders have to pump their cylinders in a bicycle store by specially designed machine. Although a tire pump is become a standard equipment for a bicycle, the requirements for pumping tires and for pumping the cylinders of suspension device are different. The pressure in tires is lower than that in the cylinders of suspension device. The tire pump can only provide lower pressure and large volume of air into the tire. The valve of the tire pump cannot bear a larger pressure as that is used for the cylinders of suspension device.
The present invention intends to provide a pump that has an inner cylinder connected to a piston in the cylinder of the pump and the two cylinders can be operated in separate so that the pump can be used to pump tires and cylinders of suspension device.